The work involved in this phase of the study will quantify amacrine synapses and bipolar synapses at several retinal loci as a function of animal age. Synapses will be expressed as number-per-neuron. Each of these growth curves will then be used as a standard of comparison for experimentally altered conditions of development. Quantitative differences from the normal curves will be used to assay the effects of thyroxin, somatotropin and prolactin upon synaptic development with the retina.